Neutron star structure from QCD

In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.Comment: Invited contribution to the EPJA Topical Issue "Exotic Matter in Neutron Stars"; 10 pages, 13 figure

EMMI Rapid Reaction Task Force on "Thermalization in Non-abelian Plasmas"

Recently, different proposals have been put forward on how thermalization proceeds in heavy-ion collisions in the idealized limit of very large nuclei at sufficiently high energy. Important aspects of the parametric estimates at weak coupling may be tested using well-established classical-statistical lattice simulations of the far-from-equilibrium gluon dynamics. This has to be confronted with strong coupling scenarios in related theories based on gauge-string dualities. Furthermore, closely related questions about far-from-equilibrium dynamics arise in early-universe cosmology and in non-relativistic systems of ultracold atoms. These were central topics of the EMMI Rapid Reaction Task Force meeting held on December 12-14, 2011, at the University of Heidelberg, which we report on.Comment: 13 pages, summary of the EMMI Rapid Reaction Task Force on "Thermalization in Non-abelian Plasmas", December 12-14, 2011, University of Heidelberg, German

Detection of SARS-CoV-2 nucleocapsid antigen from serum can aid in timing of COVID-19 infection

SARS-CoV-2 RNA can be detected in respiratory samples for weeks after onset of COVID-19 disease. Therefore, one of the diagnostic challenges of PCR positive cases is differentiating between acute COVID-19 disease and convalescent phase. The presence of SARS-CoV-2 nucleocapsid antigen in serum and plasma samples of COVID-19 patients has been demonstrated previously. Our study aimed to characterize the analytical specificity and sensitivity of an enzyme-linked immunosorbent assay (Salocor SARS-CoV-2 Antigen Quantitative Assay Kit (c) (Salofa Ltd, Salo, Finland)) for the detection of SARS-CoV-2 nucleocapsid antigen in serum, and to characterize the kinetics of antigenemia. The evaluation material included a negative serum panel of 155 samples, and 126 serum samples from patients with PCR-confirmed COVID-19. The specificity of the Salocor SARS-CoV-2 serum nucleocapsid antigen test was 98.0 %. In comparison with simultaneous positive PCR from upper respiratory tract (URT) specimens, the test sensitivity was 91.7 %. In a serum panel in which the earliest serum sample was collected two days before the collection of positive URT specimen, and the latest 48 days after (median 1 day post URT sample collection), the serum N antigen test sensitivity was 95.6 % within 14 days post onset of symptoms. The antigenemia resolved approximately two weeks after the onset of disease and diagnostic PCR. The combination of simultaneous SARS-CoV-2 antigen and antibody testing appeared to provide useful in-formation for timing of COVID-19. Our results suggest that SARS-CoV-2 N-antigenemia may be used as a diag-nostic marker in acute COVID-19.Peer reviewe

Time singularities of correlators from Dirichlet conditions in AdS/CFT

Within AdS/CFT, we establish a general procedure for obtaining the leading singularity of two-point correlators involving operator insertions at different times. The procedure obtained is applied to operators dual to a scalar field which satisfies Dirichlet boundary conditions on an arbitrary time-like surface in the bulk. We determine how the Dirichlet boundary conditions influence the singularity structure of the field theory correlation functions. New singularities appear at boundary points connected by null geodesics bouncing between the Dirichlet surface and the boundary. We propose that their appearance can be interpreted as due to a non-local double trace deformation of the dual field theory, in which the two insertions of the operator are separated in time. The procedure developed in this paper provides a technical tool which may prove useful in view of describing holographic thermalization using gravitational collapse in AdS space.Comment: 30 pages, 3 figures. Version as in JHE

Two-color QCD via dimensional reduction

We study the thermodynamics of two-color QCD at high temperature and/or density using a dimensionally reduced superrenormalizable effective theory, formulated in terms of a coarse grained Wilson line. In the absence of quarks, the theory is required to respect the Z(2) center symmetry, while the effects of quarks of arbitrary masses and chemical potentials are introduced via soft Z(2) breaking operators. Perturbative matching of the effective theory parameters to the full theory is carried out explicitly, and it is argued how the new theory can be used to explore the phase diagram of two-color QCD.Comment: 17 pages, 1 eps figure, jheppub style; v2: minor update, references added, published versio

Exploration of the phase diagram of 5D anisotropic SU(2) gauge theory

In this paper we attempt a non-perturbative study of the five dimensional, anisotropic SU(2) gauge theory on the lattice using Monte-Carlo techniques. Our goal is the exploration of the phase diagram, define the various phases and the critical boundary lines. Three phases appear, two of them are continuations of the Strong and the Weak coupling phases of pure 4d SU(2) to non-zero coupling $\beta^{'}$ in the fifth transverse direction and they are separated by a crossover transition, while the third phase is a 5D Coulombic phase. We provide evidence that the phase transition between the 5D Coulomb phase and the Weak coupling phase is a second order phase transition. Assuming that this result is not altered when increasing the lattice volume we give a first estimate of the associated critical exponents. This opens the possibility for a continuum effective five dimensional field theory.Comment: 16 pages, 10 figures, essential improvement in the study of the phase diagra

Novel flaviviruses from mosquitoes: Mosquito-specific evolutionary lineages within the phylogenetic group of mosquito-borne flaviviruses

Copyright © 2014 The Authors. Published by Elsevier Inc. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

Low incidence of severe bacterial infections in hospitalised patients with COVID-19 : A population-based registry study

Background Bacterial infections complicating COVID-19 are rare but present a challenging clinical entity. The aim of this study was to evaluate the incidence, aetiology and outcome of severe laboratory-verified bacterial infections in hospitalised patients with COVID-19. Methods All laboratory-confirmed patients with COVID-19 admitted to specialised healthcare hospitals in the Capital Province of Finland during the first wave of COVID-19 between 27 February and 21 June 2020 were retrospectively studied. We gathered the blood and respiratory tract culture reports of these patients and analysed their association with 90-day case-fatality using multivariable regression analysis. Results A severe bacterial infection was diagnosed in 40/585 (6.8%) patients with COVID-19. The range of bacteria was diverse, and the most common bacterial findings in respiratory samples were gram-negative, and in blood cultures gram-positive bacteria. Patients with severe bacterial infection had longer hospital stay (mean 31; SD 20 days) compared to patients without (mean 9; SD 9 days; p < 0.001). Case-fatality was higher with bacterial infection (15% vs 11%), but the difference was not statistically significant (OR 1.38 CI95% 0.56-3.41). Conclusions Severe bacterial infection complicating COVID-19 was a rare occurrence in our cohort. Our results are in line with the current understanding that antibiotic treatment for hospitalised COVID-19 patients should only be reserved for situations where a bacterial infection is strongly suspected. The ever-evolving landscape of the pandemic and recent advances in immunomodulatory treatment of COVID-19 patients underline the need for continuous vigilance concerning the possibility and frequency of nosocomial bacterial infections.Peer reviewe

Holographic dilepton production in a thermalizing plasma

We determine the out-of-equilibrium production rate of dileptons at rest in strongly coupled N=4 Super Yang-Mills plasma using the AdS/CFT correspondence. Thermalization is achieved via the gravitational collapse of a thin shell of matter in AdS_5 space and the subsequent formation of a black hole, which we describe in a quasistatic approximation. Prior to thermalization, the dilepton spectral function is observed to oscillate as a function of frequency, but the amplitude of the oscillations decreases when thermal equilibrium is approached. At the same time, we follow the flow of the quasinormal spectrum of the corresponding U(1) vector field towards its equilibrium limit.Comment: 21 pages, 7 figures. v2: Version accepted for publication in JHEP; minor modifications, added reference

Numerical properties of staggered quarks with a taste-dependent mass term

The numerical properties of staggered Dirac operators with a taste-dependent mass term proposed by Adams [1,2] and by Hoelbling [3] are compared with those of ordinary staggered and Wilson Dirac operators. In the free limit and on (quenched) interacting configurations, we consider their topological properties, their spectrum, and the resulting pion mass. Although we also consider the spectral structure, topological properties, locality, and computational cost of an overlap operator with a staggered kernel, we call attention to the possibility of using the Adams and Hoelbling operators without the overlap construction. In particular, the Hoelbling operator could be used to simulate two degenerate flavors without additive mass renormalization, and thus without fine-tuning in the chiral limit.Comment: 14 pages, 9 figures. V2: published version; important note added regarding Hoelbling fermions, otherwise minor change